Venetian blind assemblies especially those assemblies for use between glazings as occurs in insulated windows have to be carefully centered between the glazings to assure proper operation during tilting of the slates making up the blind assembly. Such blind assemblies are usually suspended between top and bottom fixed frame members by slat support means usually in the form of two ladder tapes which tiltably support the individual slats of the blind assembly. The ends of the slat support means are pivotally connected to pivot members which are in turn connected to the fixed frame members by hanger means. If the hanger means are not connected precisely at the center of the frame members between the glazings, there is a possibility that the edges of the slats will contact a glazing when the slats are tilted to a full open or horizontal position thus preventing full opening of all or some of the slats.
Blind assemblies as described are also subjected to variances in tension of the slat supporting means or tape ladders. This variance in tension may result from creep of the tape, which is usually made of a plastic material, occurring over a long period of time allowing the tape to become loose. If a tape is too loose, the blind assembly will not have a good closure particularly towards the bottom of the assembly. On the other hand if the tape tension is too great because of errors in maintaining tolerences during manufacturing or because of temperature changes, it may become difficult or impossible to vary the tilt of the slats of the blind assembly.
The problems of maintaining precise centering of the hanger means and of maintaining a constant uniform tension in the tape ladder has been met to some degree in the past by manufacturing and assembling blind constructions within tight limited tolerance levels which has increased cost of manufacture.
It is therefore an object of my invention to provide for a suspension system for a venetian blind assembly that may accommodate slight off-center connection of a hanger means to a fixed frame member without objectionable lateral displacement of the blind assembly.
It is a further object of my invention to provide for a suspension system in which a slat supporting means is maintained under a constant uniform tension without the necessity of maintaining close expensive manufacturing tolerances.